"Preliminary results will be given at midnight on 3 October," the SIP chairwoman, Irena Hadziabdic, said in Sarajevo, adding that the official confirmation of the elections' outcome must be given by 2 November.
These will be the sixth elections since the conclusion of the Dayton peace accords in 1995, and the third to be conducted by Bosnian authorities.
The first elections after the 1992-1995 war were organised by the Organisation for Security and Cooperation in Europe (OSCE).
A total of 3.12 million Bosnians are eligible to vote. They will elect a new state presidency, a state parliament and parliaments of the two entities -- the Croat-Muslim Federation and the Serb entity -- as well as cantonal assemblies.
The Serb republic will also elects its president and two vice-presidents.
According to SIP estimates, the elections will cost 12.6 million convertible marks (approximately EUR 6.5 million).
Voting will be organised in Bosnian embassies and consulates in 22 countries, including Croatia.
Refugees and internally displaced people will be able to vote by mail.
The polls will be held in accordance with the existing electoral legislation, which the European Court for Human Rights has found to be violating the rights of the minorities because their representatives are not allowed to run for the tripartite presidency or for seats in the upper chamber of the state parliament. Those state bodies are reserved for representatives of the three constituent peoples: Bosniaks (Muslims), Croats and Serbs.